Modified discrete cosine transforms (MDCT) and corresponding inverse modified discrete transforms (IMDCT) are used for example in audio coding and decoding techniques, such as MPEG-2 and MPEG-4 Audio Layer, Advanced Audio Coding, MPEG-4 HE-AAC, MPEG-D USAC, Dolby Digital (Plus) and other proprietary formats.
In application of such techniques, errors sometime occur due to loss of or errors in packets relating to a transform of an audio signal, before or after the packets are received in a decoding system. Such errors include for example loss or distortion of packets and may result in an audible distortion of the decoded audio signal.
Methods have thus been provided for error concealment in case errors occur in packets. The error concealment methods are generally divided into estimating concealment methods where the erroneous frames are replaced by estimations and non-estimating concealment methods for example using muting of erroneous frames, frame repetition or noise substitution.
Estimating concealment methods include methods using estimations in the frequency-domain, such as those disclosed in U.S. Pat. No. 8,620,644, and methods using estimations in the time-domain, such as those disclosed in International Pat. Pub. No. WO/2014/052746.
All techniques for concealment of errors suffer from issues relating to the trade-off between the quality of the concealment and the complexity of the estimations required. Hence, there is a need for further methods for error concealment.
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